The present invention relates to a method, a device and a computer program for determining the blood flow in a tissue or organ region.
A method for determining the depth of burns in tissue is known from U.S. Pat. No. 5,074,306, in which the fluorescence of the exogenous chromophore indocyanine green is detected and the depth of burn wounds is determined on the basis of its distribution in the tissue.
In “Annals of Plastic Surgery”. 1999, Vol. 42, pp. 266-274 a device and a method for measuring the blood circulation through transferred skin flaps is described, wherein after applying indocyanine green the fluorescence stimulated by irradiation with a pulsed laser array is detected with a CCD camera.
In the case of the known methods and known devices only the relative fluorescence distribution of the chromophore indocyanine green in the tissue is examined qualitatively to establish the blood circulation through the tissue. The known methods are not suitable for determining the regional blood flow quantitatively on the basis of the fluorescence signal.
A method and a device for determining circulation through the brain and the intracranial blood volume is disclosed in WO 96/16594.
A method and arrangement for the non-invasive determination of cerebral blood flow by means of near infrared spectroscopy is known from WO 98/08434.
The methods of the two last-mentioned publications are based on the invasive or non-invasive spectroscopic measurement of the chromophore indocyanine green on the basis of its absorption behaviour in the near infrared spectral range. Moreover, these methods are not suitable for confining the tissue or organ region to be examined to a precisely defined area.